1. Field of the Invention
This invention relates to electrical devices comprising resistive heating elements, in particular self-regulating strip heaters which comprise resistive heating elements composed of a conductive polymer composition which exhibits PTC behavior.
2. Introduction to the Invention
For many applications, it is desirable to heat a substrate, e.g. a pipe or a tank, by means of an elongate heater comprising a resistive heating element. Often it is necessary to provide an electrically insulating jacket around the resistive heating element in order to prevent electrical shorting between the resistive element and an electrically conductive substrate. While such insulating jackets provide electrical insulation and environmental protection, they may not have adequate abrasion resistance. As a result, braids are sometimes provided over the insulating jacket for toughness and abrasion resistance. When the braid is metallic, it can also act as a grounding braid.